High impact information on Macronucleus

• In contrast, wild-type macronuclear rDNA of the C3 strain used to obtain the mutant outreplicated B strain rDNA in B/C3 heterozygote macronuclei [1].
• The short DNA molecules of the macronucleus are terminated with repeats of the octanucleotide C4A4 [2].
• Two dimensional gel electrophoresis (triton-acid-urea followed by SDS) has been used to resolve two previously uncharacterized, quantitatively minor histone variants in acid extracts from macronuclei of Tetrahymena thermophila [3].
• In contrast, telomerase from vegetative macronuclei used only the cleavage pathway [4].
• Telomere repeat addition onto non-telomeric 3' ends was lost when developing macronuclei were lysed and the contents purified on glycerol gradients [4].

Biological context of Macronucleus

• In the present study we show that when a 1.77 kb BamHI DNA fragment harbouring the his3 gene of Saccharomyces cerevisiae was microinjected into the macronucleus, a fraction of the molecules are integrated into the chromosome via an illegitimate recombination process [5].
• The existence of this intron demonstrates that, despite the elimination of 95% of the micronuclear genome from the developing macronucleus, at least some noncoding DNA is retained during macronuclear development of hypotrichous ciliates [6].
• DNA in the polyploid macronucleus of the ciliated protozoan Tetrahymena thermophila contains the modified base N6-methyladenine [7].
• In contrast to yeast ORCs, TIF4 DNA binding activity was cell cycle regulated and peaked during S phase, coincident with the redistribution of the Orc2-related subunit, p69, from the cytoplasm to the macronucleus [8].
• We present evidence that TMP and centrin genes identified in the macronucleus are also present in the micronucleus, ruling out the possibility that these novel multigene families are generated by somatic rearrangements during macronuclear development [9].

Associations of Macronucleus with chemical compounds

• We completely replaced the single type of alpha-tubulin gene in the macronucleus with a version encoding arginine instead of lysine 40 and therefore cannot be acetylated at this position [10].
• Histone H3 that is methylated at lysine 9 (K9) is a hallmark of heterochromatin and, in Tetrahymena, is found only in developing macronuclei (anlagen) in association with chromatin containing the sequences undergoing elimination [11].
• Deoxyribonucleic acid (DNA) of the transcriptionally active macronucleus of Tetrahymena thermophila is methylated at the N6 position of adenine to produce methyladenine (MeAde); approximately 1 in every 125 adenine residues (0.8 mol%) is methylated [12].
• To test the notion that the somatic nucleus (macronucleus) is involved in this compensation, cells possessing micronuclei were treated with 5-azacytidine during sexual reproduction when new somatic nuclei develop [13].
• Exposure to the alkylating agent methyl methane sulfonate also resulted in substantially elevated Rad51 protein levels in treated cells, with pronounced localization in the macronucleus [14].

Gene context of Macronucleus

• In this report, we demonstrate that either the HTA1 gene or the HTA2 gene, encoding the major H2As, can be completely replaced by disrupted genes in the polyploid, transcriptionally active macronucleus, indicating that neither of the two genes is essential [15].
• Using polyclonal antibodies raised against yeast p34cdc2, we have detected a 36 kd immunoactive polypeptide in macronuclei which binds to Suc1 (p13)-coated beads and closely follows H1 kinase activity [16].
• Tightly bound PCNA/cyclin was localized at the site of DNA synthesis in macronuclei, the rear zone of the replication band [17].
• Furthermore, we demonstrate that macronuclei from Tetrahymena contain a growth-associated H1 kinase activity which closely resembles cdc2 kinase from other eukaryotes [16].
• In vitro generated antibodies specific for telomeric guanine-quadruplex DNA react with Stylonychia lemnae macronuclei [18].

Analytical, diagnostic and therapeutic context of Macronucleus

• Triton-acid-urea gel electrophoresis of an acid extract of Euplotes macronuclei revealed enhanced silver reaction with a single protein upon selective silver staining [19].

References